1. Field of the Invention
The present invention relates to a resin encapsulation molding method of an electronic part, in which a vacuum mechanism and a release film are used in combination when providing resin encapsulation molding to a substrate to which the electronic part is mounted, and a resin encapsulation apparatus used therefor.
2. Description of the Background Art
Conventionally, resin encapsulation molding has been provided to a semiconductor chip attached to a substrate. In the resin encapsulation molding, a resin encapsulation molding apparatus is used that includes a mold and a release film for providing the resin encapsulation molding to an electronic part. A conventional resin encapsulation molding apparatus is provided with, for example as shown in FIG. 8, a mold consisting of an upper mold 31 and a lower mold 32. Further, the resin encapsulation molding apparatus is provided with a release film supplying mechanism (not shown) for providing a release film 34 between upper mold 31 and lower mold 32, applying a prescribed tension to release film 34.
The resin encapsulation molding apparatus is further provided with a seal member 42 for making the inside of the mold to an outer air blocking space 41 before the mold is clamped. Further, the resin encapsulation molding apparatus is provided with a vacuum mechanism (not shown) for evacuating outer air blocking space 41.
Using the resin encapsulation molding apparatus, a substrate 36 is provided with resin encapsulation molding. Substrate 36 is provided with a semiconductor chip (an electronic part) 37 and a wire 38 that electrically connects substrate 36 and chip 37. Further, as shown in FIG. 8, a cavity 35 is provided to a mold surface 33 of lower mold 32. Cavity 35 is filled with a molten resin. At this time, chip 37 and wire 38 are commonly provided with resin encapsulation molding.
Further, for example as shown in FIG. 8, a suction port 40 communicating with a mechanism for suctioning a release film (not shown) is provided to the bottom surface of cavity 35 of lower mold 32. By the function of this mechanism for suctioning the release film, release film 34 covers cavity 35 of lower 32 conforming to the contour thereof, with a prescribed tension.
Still further, fixing means 39 are provided to mold surface 33 of upper mold 31 for fixing the position of substrate 36. As shown in FIG. 8, substrate 36 can be fixed to upper mold 31, with semiconductor chip 37 and wire 38 facing downward.
Still further, before clamping upper mold 31 and lower mold 32, as shown in FIG. 8, release film 34 is suctioned to cavity 35 of lower mold 32. At this time, seal member 42 provided to mold surface 33 of upper mold 31 serves to form outer air blocking space 41. In this state, by the function of the vacuum mechanism, outer air blocking space 41 is forcibly evacuated through air vacuum hole 43.
More specifically, the conventional resin encapsulation molding method is as follows.
First, upper mold 31 and lower mold 32 are mold-open (unclamped). Then, the main surface of substrate 36 to which semiconductor chip 37 and wire 38 are attached is faced downward. In this state, fixing means 39 are activated to attach substrate 36 to mold surface 33 of upper mold 31. Additionally, release film 34 with a prescribed tension covers along the surface of cavity 34 of lower mold 32. This is performed by evacuating air from the mold through release film suction port 40. Subsequently, before upper mold 31 and lower mold 32 are clamped, the function of seal member 42 is used to form outer air blocking space 41 by release film 34 covering along the surface of cavity 35 of lower mold 32 and upper mold 31.
Then, as shown in FIG. 8, outer air blocking space 41 is evacuated through air vacuum hole 43 by the function of the vacuum mechanism. Then, in the state performing the evacuation of the mold, upper mold 31 and lower mold 32 are completely clamped. Next, cavity 35 covered by release film 34 is filled with a molten resin. Thus, the molten resin covers semiconductor chip 37 and wire 38 mounted on substrate 36. Thereafter, the molten resin cures. As a result, an encapsulated substrate, in which the cured resin is formed on substrate 36, is formed.
However, in the conventional resin encapsulation molding apparatus, there is a difference in the magnitude between a suction force A and a suction force B shown in FIG. 8. Suction force A is for evacuating through suction hole 40. In other words, suction force A is for causing release film 34 to cover mold surface 33 of lower mold 32 and the contour of cavity 35. Further, suction force B is for evacuating through air vacuum hole 43. In other words, suction force B is for forming outer air blocking space 41 between release film 34 and upper mold 31 using seal member 42 provided on mold surface 33 of upper mold 31.
In the conventional resin encapsulation molding apparatus, the difference between two suction forces A and B adversely affects the resin encapsulation molding. Consider a case in which suction force B is greater than suction force A. In this case, the air in the space of cavity 35 is suctioned. Therefore, as shown in FIG. 8, release film 34 covering along the contour of cavity 35 indicated by a dash-dot-dot line moves to the space in cavity 35 become wavy release film 34 indicated by a solid line. Thus, there arises a problem that release film 34 contacts the wire 38 in the space of cavity 35.
Upper mold 31 and lower mold 32 are clamped with release film 34 waved in the space of cavity 35 as shown in FIG. 8. At this time, a problem arises that wire 38 attached to substrate 36 (semiconductor chip 37 and wire 38) is deformed or severed.